Chafing is skin irritation that occurs where skin rubs against skin, clothing, shoes, or other materials. Chafing sometimes refers to red, sore skin that has been irritated by something rubbing against it. Skin chafing is a problem typically experienced in sports or in the armed services in connection with activities such as running, jogging, hiking, etc. The U.S. Army has contracted with companies to develop and provide special apparel with low friction fiber technology to integrate into various components of the soldier's uniform, for the sole purpose of reducing blisters caused by chafing of the skin. Skin chafing is also a problem in infants in the form of “diaper rash.” “Diaper rash” has been defined by the U.S. Food and Drug Administration as an inflammatory skin condition in the diaper area (perineum, buttocks, lower abdomen, and inner thighs) caused by factors including chaffing or mechanical (21 CFR §347.3 (1990)).
Solutions to the chafing problem in the prior art range from applications of petroleum jelly or talcum powder as a lubricant on the affected areas of the skin to temporarily alleviate the irritation, or wearing apparel, such as spandex and nylon, to keep body parts from rubbing together, resulting in chafing. Special formulations have been developed such as BODYGLIDE™ skin formulae, containing plant-derived triglycerides or waxes, for topical application on the skin. The application of formulae such as petroleum jelly, plant-derived waxes, or beeswaxes, etc. may create problems in some individuals when the formulae results in blocked skin pores or a greasy or messy residue.
Boron nitride is a ceramic material with unique properties including lubricity, high thermal conductivity, low wear, and low thermal expansion. It has been used in a wide variety of applications, ranging from industrial applications such as thermal spray coatings, thermal management greases, metallization boats, etc., to “high-tech” applications such as neutron detectors in homeland security systems.
Boron nitride has been used in some cosmetic applications such as lipsticks, foundations, and face powders, where softness, lubricity, and opacity properties are desired. It has also been disclosed for topical applications such as body powder. European Patent Publication No. EP 1055422 discloses the use of boron nitride (“BN”) in a cosmetic or dermatological formulation, which includes iron-titanium mixed oxide particles, to improve the skin feel and protect the skin from the effects of light, particularly sunlight. BN, in this dermatological formulation, improves the light protective effect of the mixed oxide particles as the bare skin is exposed to sunlight. U.S. Pat. No. 6,824,763 discloses a body powder, which includes a topical anti-fungal agent in combination with at least two excipients, with a boron nitride particulate material coated with a silicone compound as one of the two excipients.
There is still a need for solutions to the skin chafing problem. Applicants have found that boron nitride, with its unique lubricity and thermal conductivity properties, can be used in an anti-chafing composition to minimize skin irritation problems when the skin is in contact with itself or with another surface, and can provide relief and comfort to the wearer.